Influence of Land-Cover Heterogeneity on the Runoff Reduction and Stormwater Retention Performance of Low Impact Development Interventions

Urban pluvial flooding is becoming more severe in rapidly urbanizing cities under increasingly frequent extreme rainfall. Although Low Impact Development (LID) is widely used to improve infiltration and on-site stormwater retention, its hydrological performance may differ greatly across urban functional zones with distinct land-cover patterns, development intensity, and retrofit constraints. To address the lack of comparative evidence under consistent conditions, this study mapped land cover in five representative functional zones in Nanjing—old residential, new residential, commercial, industrial, and cultural/educational areas—and applied a unified CITYgreen (SCS-CN) framework under a 72 mm, 24 h, two-year design storm to simulate four standalone LID measures: ground-level greening, permeable pavement, green roofs, and grassed swales. Results showed big zone-dependent differences in hydrological benefits. Runoff reduction was greatest in highly impervious industrial and commercial areas, whereas the new residential zone showed only a marginal improvement due to its relatively favorable baseline retention conditions. Across all zones, measures that enhanced infiltration and near-surface storage performed best, with ground-level greening and permeable pavement achieving the highest retention efficiency. These findings highlight the importance of zoning-based, context-sensitive LID prioritization for urban renewal, sponge-city retrofitting, and stormwater planning in rapidly urbanizing cities.